Today I went to get gas and instead of stopping on its own it overflowed on my car. The last time I went to get gas it stopped at 3/4 full and wouldn't let me fill up any more. What could be causing this? Help please.

 

I think that if the tank gets too low and we fill it up air gets trapped in some part of the tank and once we start driving off the gas sloshes around and evens the air out and next thing you know we are missing a portion of our gas tank to air.

 

when it only filled up 3/4 of the way I knew it wasn't full because of the price. And when I started it up it showed 3/4 full right away.